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Received: from smtp-auth.mailprotect.be ([178.208.39.155]) by com-mpt-out001.mailprotect.be with esmtp (Exim 4.89) (envelope-from ) id 1gWqHp-0005NF-HB; Tue, 11 Dec 2018 23:13:54 +0100 Received: from desktop-bart.svl.corp.google.com (unknown [104.133.8.89]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp-auth.mailprotect.be (Postfix) with ESMTPSA id A9472C09DB; Tue, 11 Dec 2018 23:13:51 +0100 (CET) From: Bart Van Assche To: peterz@infradead.org Cc: mingo@redhat.com, tj@kernel.org, longman@redhat.com, johannes.berg@intel.com, linux-kernel@vger.kernel.org, Bart Van Assche , Johannes Berg Subject: [PATCH v4 08/15] locking/lockdep: Reuse list entries that are no longer in use Date: Tue, 11 Dec 2018 14:13:14 -0800 Message-Id: <20181211221321.196536-9-bvanassche@acm.org> X-Mailer: git-send-email 2.20.0.rc2.403.gdbc3b29805-goog In-Reply-To: <20181211221321.196536-1-bvanassche@acm.org> References: <20181211221321.196536-1-bvanassche@acm.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Originating-IP: 178.208.39.155 X-SpamExperts-Domain: mailprotect.be X-SpamExperts-Username: 178.208.39.128/27 Authentication-Results: mailprotect.be; 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Cc: Peter Zijlstra Cc: Waiman Long Cc: Johannes Berg Signed-off-by: Bart Van Assche --- kernel/locking/lockdep.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 82dd7d2851eb..2da45621f741 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include #include @@ -132,6 +133,7 @@ static inline int debug_locks_off_graph_unlock(void) unsigned long nr_list_entries; static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; +static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_ENTRIES); /* * All data structures here are protected by the global debug_lock. @@ -296,6 +298,7 @@ static struct pending_free { struct list_head zapped_classes; struct rcu_head rcu_head; bool scheduled; + DECLARE_BITMAP(list_entries_being_freed, MAX_LOCKDEP_ENTRIES); } pending_free[2]; static DECLARE_WAIT_QUEUE_HEAD(rcu_cb); @@ -891,7 +894,10 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) */ static struct lock_list *alloc_list_entry(void) { - if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { + int idx = find_first_zero_bit(list_entries_in_use, + ARRAY_SIZE(list_entries)); + + if (idx >= ARRAY_SIZE(list_entries)) { if (!debug_locks_off_graph_unlock()) return NULL; @@ -899,7 +905,9 @@ static struct lock_list *alloc_list_entry(void) dump_stack(); return NULL; } - return list_entries + nr_list_entries++; + nr_list_entries++; + __set_bit(idx, list_entries_in_use); + return list_entries + idx; } /* @@ -1003,7 +1011,7 @@ static inline void mark_lock_accessed(struct lock_list *lock, unsigned long nr; nr = lock - list_entries; - WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ lock->parent = parent; lock->class->dep_gen_id = lockdep_dependency_gen_id; } @@ -1013,7 +1021,7 @@ static inline unsigned long lock_accessed(struct lock_list *lock) unsigned long nr; nr = lock - list_entries; - WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ return lock->class->dep_gen_id == lockdep_dependency_gen_id; } @@ -4281,13 +4289,14 @@ static void zap_class(struct pending_free *pf, struct lock_class *class) * Remove all dependencies this lock is * involved in: */ - for (i = 0, entry = list_entries; i < nr_list_entries; i++, entry++) { + for_each_set_bit(i, list_entries_in_use, ARRAY_SIZE(list_entries)) { + entry = list_entries + i; if (entry->class != class && entry->links_to != class) continue; + if (__test_and_set_bit(i, pf->list_entries_being_freed)) + continue; + nr_list_entries--; list_del_rcu(&entry->entry); - /* Clear .class and .links_to to avoid double removal. */ - WRITE_ONCE(entry->class, NULL); - WRITE_ONCE(entry->links_to, NULL); } if (list_empty(&class->locks_after) && list_empty(&class->locks_before)) { @@ -4329,8 +4338,9 @@ static bool inside_selftest(void) } /* - * Free all lock classes that are on the pf->zapped_classes list. May be called - * from RCU callback context. + * Free all lock classes that are on the pf->zapped_classes list and also all + * list entries that have been marked as being freed. Called as an RCU + * callback function. May be called from RCU callback context. */ static void free_zapped_classes(struct rcu_head *ch) { @@ -4346,6 +4356,9 @@ static void free_zapped_classes(struct rcu_head *ch) reinit_class(class); } list_splice_init(&pf->zapped_classes, &free_lock_classes); + bitmap_andnot(list_entries_in_use, list_entries_in_use, + pf->list_entries_being_freed, ARRAY_SIZE(list_entries)); + bitmap_clear(pf->list_entries_being_freed, 0, ARRAY_SIZE(list_entries)); graph_unlock(); restore_irqs: raw_local_irq_restore(flags); -- 2.20.0.rc2.403.gdbc3b29805-goog